Thanks for your answer.

@marinheiro
I have similar problem.
I cant downgrade Lenovo x606f(4/128) to Android 9 from 10
I found instructions here
https://forums.ubports.com/post/67905
Successfully make flashing according instructions at Windows 10, but my Lenovo x606f is still have Android 10?! How to resolve this, anybody help, please.

Sure you have 605 and not 606?

@codenul
I recently needed a tablet, and seeing that the 606f has an UT port, and is still sold pristine at a good price, i bought one.

Sad if the port is not mentained anymore and won't reach stable state, i lost my bet lol.

I'll keep it under android though.